Reaction of acetylene with alkyl substituted benzenes



2,718,533 Patented Sept. 20,1955

U t statesPatfii m REACTION -'OF ACETY-LE'N E WITH ALKYL SUBSTITUTED Edwin 'SmoIinQStamfoi-d, Conn assignor to American Cyanami'd Company, New York, N. Y., a

corporation of Maine No Drawing. Application July 23, 1 954, Serial No. 445,460

5 Claims. (Cl. 260-668) This invention relates to a process of producing diaryl parafiins and, more particularly, to a process of producing 1,1-diarylethanes by the reaction of acetylene with a monoor di-alkyl substituted benzene.

Paraffins having at least two carbon atoms and having two aryl substituents attached to one of said carbon atoms have been produced in the past by a number of different reactions. Thus, for example, a monoor di-alkyl substituted benzene has been reacted with paraldehyde in the presence of hydrogen fluoride to form a 1,1-diarylethane. It has also been proposed to react acetylene with a monoor di-alkyl substituted benzene in the presence of a sulfuric acid-mercuric sulfate catalyst for the production of 1,1-diarylethanes. I have now found a novel catalyst which is effective for the reaction of acetylene with a monoor di-alkyl substituted benzene for the production of 1,1-diarylethanes.

The diarylethanes produced in accordance with my invention are useful as insecticides or as starting materials in the production of insecticides and as starting materials in the production of wetting agents. The diarylethanes produced are especially important in that they may be cracked to produce ringor nuclear-substituted styrenes which may be polymerized to form synthetic resinous compositions useful in the production of films, castings and molded objects.

It is therefore an object of my invention to provide a new method for the production of paraflins having at least two carbon atoms and having two aryl substituents attached to one of said carbon atoms. It is a further object of my invention to prepare 1,1-diarylethanes by the reaction of acetylene with a monoor di-alkyl substituted benzene in the presence of a novel catalyst therefor. These and other objects of my invention will be discussed more fully hereinbelow.

I have found that the reaction of acetylene with monoor di-alkyl substituted benzene for the production of a 1,1- diarylethane may be carried out in the presence of a sulfuric acid-vanadium pentoxide-sodium sulfate catalyst. Sulfuric acid of concentrations of from about 85% to about 105%, preferably from about 88% to about 98.5%, may be employed in the present process. The amount of sulfuric acid that is used in the process may vary over rather wide limits, for example, from about one part of sulfuric acid per part of substituted benzene charged to about one part of sulfuric acid to about 25 parts of substituted benzene charged. However, it is preferred that from about 1:12 to about 1:5 parts of sulfuric acid be employed per part of substituted benzene. The vanadium pentoxide and sodium sulfate may be dispersed in the sulfuric acid that is introduced into the reaction mixture or the vanadium pentoxide and sodium sulfate may beseparately introduced into the reaction mixture. Other obvious methods of introduction of the catalyst into the reaction mixture will be apparent to those skilled in th art. The total amount of vanadium pentoxide and sodium sulfate employed in the instant process may vary from about 0.5% by weight up to about 20% by weight, based on the total weight of concentrated sulfuric acid utilized. It is preferred, however, that the total amount of vanadium pentoxide and sodium sulfate be about 5% by Weight, based on the to'tal weight of concentrated sulfuric acid present. The proportions of vanadium pentoxide to sodiurn sulfate may vary from about 1:99 to 99:1, respectively.

In order that those skilled in the art may more fully understand the inventive concept herein presented, the -fol lowing example is given byway of illustration and not limitation unlessv otherwise noted in the appended claims. All parts are parts by weight.

Example To a vigorously stirred mixture of 428 parts of toluene and 42.5 parts of 95.5% sulfuric acid, maintained at 10 C. to 12 C., were added 1.5 parts of vanadium pentoxide and 1.0 part of sodium sulfate. Gaseous acetylene was bubbled into the reaction mixture for 40 minutes at the rate of 0.015 mol per minute. The liquid phases obtained were separated and the organic layer was washed with aqueous sodium hydroxide solution and distilled. 1,1-ditolylethane representing a yield of 47%, based on toluene used up, was obtained.

The stoichiometry of the present reaction requires that two mols of the monoor di-alkyl substituted benzene react with each mol of acetylene for the formation of the diaryl substituted paraifin. In order to obtain optimum yields of the diaryl substituted paraffin, it is preferred that from about 15% to about 45% of the stoichiometric amount of acetylene theoretically required to react with all of the substituted benzene be employed herein. By thus limiting the amount of acetylene that is introduced into the reaction mixture, deleterious side reactions are minimized.

Examples of monoand di-alkyl substituted benzenes that may be utilized in the process of my invention are such as toluene, 0-, m and p-xylenes, ethylbenzene and the like. Long-chain monoand di-alkyl substituted benzenes may also be employed in the process of my invention when such materials are available.

A convenient method of carrying out the present reaction of my invention is to charge the desired amount of substituted benzene into a suitable reaction vessel which is then cooled to about 5 C. below the desired reaction temperature. Stirring of the substituted benzene is then begun and the sulfuric acid catalyst then introduced therein. As previously stated, the sulfuric acid may contain the metallic salt or the metallic salt may be separately introduced into the mixture. The reaction may be carried out at temperatures ranging from about 20 C. to about C. Stirring of the mixture is maintained throughout the reaction to emulsify the acid and the hydrocarbons and to prevent catalyst deposition at the bottom of the reactor. The desired calculated amount of acetylene is then introduced into the reactor at the desired rate. After the acetylene addition is complete, stirring of the reaction mixture is discontinued, the reaction mixture is separated into two layers, the organic layer washed with an aqueous caustic solution and the 1,1-diary-lethane recovered therefrom by distillation. When the reaction is carried out at below 0 C., the reaction mixture is more difiicult to work up and the separation of the acid layer from the desired product is slower. Therefore, it is preferred that a temperature range of from about 0 C. to about 45 C. be employed in the process.

The process of my invention may be carried out as a batch, semicontinuous or as a single or multistage continuous operation. Inasmuch as a semicontinuous or batch operation inherently entails an increased number of manual procedural steps and a single stage continuous reaction produces lower yields, it is desirable to carry out the reaction in a multistage continuous reactor.

carbon atoms and having two aryl substituents attached to one of said carbon atomswherein acetylene is reacted with amemhergselected;from the group consisting of monoand di-alkyl substituted benzenes, the improvement which comprises carrying out the reaction in the presence of a sulfuric acid-vanadium pentoxide-sodium sulfate. catalyst.

'2. In the preparation oi a 1,1-diarylethane wherein acetylene is reacted with a member selected from the group consisting of monoand di-alkyl substituted benzene, thevimprovement which comprises carrying out the reaction in the presence of a' sulfuric acid-vanadium pentoxide-sodium sulfate catalyst 3. In the preparation of 1,1-ditolylethane wherein aceti c ylene is reaeted with toluene, the improvement which -klntthe Prepa ion 9f. apar fl h in tl as wo.,,

comprises ...carrying out the reactionninrthe presence ,of a sulfuric acid-vanadium pentoxide-sodium sulfate catalyst.

4. In the preparation of lil-dixylylethane wherein acetylene is reacted with Xylene, the improvement which comprises carrying out the reaction in the presence of a sulfuric acid-vanadium pentoXide-sodium sulfate catalyst.

5. In the preparation of ,1,1-bis'(ethylphenyl') ethane wherein acetylene is reacted with ethylbenzene, the improvement which comprises carrying out the reaction in the presence of a sulfuric acid-vanadium pentoXide-sodium sulfate catalyst.

References Cited in the file of this patent Reilly et al., Iour; Am; Chern. 'Soc., vol. 50 (1928), pages 25642566. 

1. IN THE PREPARATION OF A PARAFFIN HAVING AT LEAST TWO CARBON ATOMS AND HAVING TWO ARYL SUBSTITUENTS ATTACHED TO ONE OF THE SAID CARBON ATOMS WHERIN ACETYLENE IS REACTED WITH A MEMBER SELECTED FROM THE GROUP CONSISTING OF MONO- AND DI-ALKYL SUBSTITUTED BENZENES, THE IMPROVEMENT WHICH COMPRISES CARRYING OUT THE REACTION IN THE PRESENCE OF A SULFURIC ACID-VANADIUM PENTOXIDE-SODIUM SULFATE CATALYST. 